U.S. Pat. No. 7,005,452 discloses novel therapeutics that are useful in the treatment of disorders that can be managed by inhibition of norepinephrine (NE) and serotonin (5-HT) reuptake, for example, anxiety disorders and depression (e.g., major depressive disorder). One compound disclosed in the '452 patent which is believed to be particularly effective for treating these types of disorders is (1S,2R)-2-(amino methyl)-N,N-diethyl-1-phenyl cyclopropane carboxamide. The structural formula of (1S,2R)-2-(amino methyl)-N,N-diethyl-1-phenyl cyclopropane carboxamide is:
The entire contents of the '452 patent are hereby incorporated by reference in their entirety.
The present invention relates to the solid state physical properties of (1S,2R)-2-(amino methyl)-N,N-diethyl-1-phenyl cyclopropane carboxamide. These properties may be influenced by controlling the conditions under which this compound is obtained in solid form. Solid state physical properties include, for example, the flowability of the milled solid. Flowability affects the ease with which the material is handled during processing into a pharmaceutical product. When particles of the powdered compound do not flow past each other easily, a formulation specialist must take that fact into account in developing a tablet or capsule formulation, which may necessitate the use of glidants such as colloidal silicon dioxide, talc, starch or tribasic calcium phosphate.
Another important solid state physical property of a pharmaceutical compound is its rate of dissolution in solution which may have therapeutic consequences since it imposes an upper limit on the rate at which an orally-administered active ingredient may reach the patient's bloodstream. The solid state form of a compound may also affect its behavior on compaction and its storage stability.
These practical physical characteristics are influenced by the conformation and orientation of molecules in the unit cell, which defines a particular crystalline or polymorphic form of a substance. The crystalline or polymorphic form may give rise to thermal behavior different from that of the amorphous material or another crystalline or polymorphic form. Thermal behavior is measured in the laboratory by such techniques as capillary melting point, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and may be used to distinguish some crystalline or polymorphic forms from others. A particular crystalline or polymorphic form may also give rise to distinct spectroscopic properties that may be detectable by X-ray powder diffraction (XRPD), solid state nuclear magnetic resonance (NMR) spectrometry, Raman spectroscopy and infrared (IR) spectrometry.
In deciding which polymorph or crystalline form is preferable, the numerous properties of the polymorphs or crystalline forms must be compared and the preferred polymorph or crystalline form chosen based on the many physical property variables. It is entirely possible that one polymorph or crystalline form can be preferable in some circumstances in which certain aspects, such as ease of preparation, stability, etc., are deemed to be critical. In other situations, a different crystalline form or polymorph may be preferred for greater solubility and/or superior pharmacokinetics.
The discovery of new crystalline or polymorphic forms of a pharmaceutically useful compound provides a new opportunity to improve the performance characteristics of a pharmaceutical product. It enlarges the repertoire of materials that a formulation scientist has available for designing, for example, a pharmaceutical dosage form of a drug with a targeted release profile or other desired characteristic. New crystalline forms of (1S,2R)-2-(amino methyl)-N,N-diethyl-1-phenyl cyclopropane carboxamide have now been discovered.